@c This is part of the Emacs manual.
-@c Copyright (C) 1997, 1999, 2000, 2001 Free Software Foundation, Inc.
+@c Copyright (C) 1997, 1999, 2000, 2001, 2002, 2003, 2004,
+@c 2005, 2006, 2007 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node International, Major Modes, Frames, Top
@chapter International Character Set Support
@cindex Dutch
@cindex Spanish
Emacs supports a wide variety of international character sets,
-including European variants of the Latin alphabet, as well as Chinese,
-Cyrillic, Devanagari (Hindi and Marathi), Ethiopic, Greek, Hebrew, IPA,
-Japanese, Korean, Lao, Thai, Tibetan, and Vietnamese scripts. These features
-have been merged from the modified version of Emacs known as MULE (for
-``MULti-lingual Enhancement to GNU Emacs'')
-
- Emacs also supports various encodings of these characters used by
+including European and Vietnamese variants of the Latin alphabet, as
+well as Cyrillic, Devanagari (for Hindi and Marathi), Ethiopic, Greek,
+Han (for Chinese and Japanese), Hangul (for Korean), Hebrew, IPA,
+Kannada, Lao, Malayalam, Tamil, Thai, Tibetan, and Vietnamese scripts.
+Emacs also supports various encodings of these characters used by
other internationalized software, such as word processors and mailers.
Emacs allows editing text with international characters by supporting
@itemize @bullet
@item
-You can visit files with non-ASCII characters, save non-ASCII text, and
-pass non-ASCII text between Emacs and programs it invokes (such as
+You can visit files with non-@acronym{ASCII} characters, save non-@acronym{ASCII} text, and
+pass non-@acronym{ASCII} text between Emacs and programs it invokes (such as
compilers, spell-checkers, and mailers). Setting your language
environment (@pxref{Language Environments}) takes care of setting up the
coding systems and other options for a specific language or culture.
Alternatively, you can specify how Emacs should encode or decode text
-for each command; see @ref{Specify Coding}.
+for each command; see @ref{Text Coding}.
@item
-You can display non-ASCII characters encoded by the various scripts.
-This works by using appropriate fonts on X and similar graphics
-displays (@pxref{Defining Fontsets}), and by sending special codes to
-text-only displays (@pxref{Specify Coding}). If some characters are
-displayed incorrectly, refer to @ref{Undisplayable Characters}, which
-describes possible problems and explains how to solve them.
+You can display non-@acronym{ASCII} characters encoded by the various
+scripts. This works by using appropriate fonts on graphics displays
+(@pxref{Defining Fontsets}), and by sending special codes to text-only
+displays (@pxref{Terminal Coding}). If some characters are displayed
+incorrectly, refer to @ref{Undisplayable Characters}, which describes
+possible problems and explains how to solve them.
@item
-You can insert non-ASCII characters or search for them. To do that,
+You can insert non-@acronym{ASCII} characters or search for them. To do that,
you can specify an input method (@pxref{Select Input Method}) suitable
for your language, or use the default input method set up when you set
-your language environment. (Emacs input methods are part of the Leim
-package, which must be installed for you to be able to use them.) If
-your keyboard can produce non-ASCII characters, you can select an
-appropriate keyboard coding system (@pxref{Specify Coding}), and Emacs
+your language environment. If
+your keyboard can produce non-@acronym{ASCII} characters, you can select an
+appropriate keyboard coding system (@pxref{Terminal Coding}), and Emacs
will accept those characters. Latin-1 characters can also be input by
-using the @kbd{C-x 8} prefix, see @ref{Single-Byte Character Support,
-C-x 8}.
+using the @kbd{C-x 8} prefix, see @ref{Unibyte Mode}.
+
+On X Window systems, your locale should be set to an appropriate value
+to make sure Emacs interprets keyboard input correctly; see
+@ref{Language Environments, locales}.
@end itemize
The rest of this chapter describes these issues in detail.
* Coding Systems:: Character set conversion when you read and
write files, and so on.
* Recognize Coding:: How Emacs figures out which conversion to use.
-* Specify Coding:: Various ways to choose which conversion to use.
+* Specify Coding:: Specifying a file's coding system explicitly.
+* Output Coding:: Choosing coding systems for output.
+* Text Coding:: Choosing conversion to use for file text.
+* Communication Coding:: Coding systems for interprocess communication.
+* File Name Coding:: Coding systems for file @emph{names}.
+* Terminal Coding:: Specifying coding systems for converting
+ terminal input and output.
* Fontsets:: Fontsets are collections of fonts
that cover the whole spectrum of characters.
* Defining Fontsets:: Defining a new fontset.
* Undisplayable Characters:: When characters don't display.
-* Single-Byte Character Support::
- You can pick one European character set
- to use without multibyte characters.
+* Unibyte Mode:: You can pick one European character set
+ to use without multibyte characters.
+* Charsets:: How Emacs groups its internal character codes.
@end menu
@node International Chars
@section Introduction to International Character Sets
- The users of international character sets and scripts have established
-many more-or-less standard coding systems for storing files. Emacs
-internally uses a single multibyte character encoding, so that it can
-intermix characters from all these scripts in a single buffer or string.
-This encoding represents each non-ASCII character as a sequence of bytes
-in the range 0200 through 0377. Emacs translates between the multibyte
-character encoding and various other coding systems when reading and
-writing files, when exchanging data with subprocesses, and (in some
-cases) in the @kbd{C-q} command (@pxref{Multibyte Conversion}).
+ The users of international character sets and scripts have
+established many more-or-less standard coding systems for storing
+files. Emacs internally uses a single multibyte character encoding,
+so that it can intermix characters from all these scripts in a single
+buffer or string. This encoding represents each non-@acronym{ASCII}
+character as a sequence of bytes in the range 0200 through 0377.
+Emacs translates between the multibyte character encoding and various
+other coding systems when reading and writing files, when exchanging
+data with subprocesses, and (in some cases) in the @kbd{C-q} command
+(@pxref{Multibyte Conversion}).
@kindex C-h h
@findex view-hello-file
The prefix key @kbd{C-x @key{RET}} is used for commands that pertain
to multibyte characters, coding systems, and input methods.
-@ignore
-@c This is commented out because it doesn't fit here, or anywhere.
-@c This manual does not discuss "character sets" as they
-@c are used in Mule, and it makes no sense to mention these commands
-@c except as part of a larger discussion of the topic.
-@c But it is not clear that topic is worth mentioning here,
-@c since that is more of an implementation concept
-@c than a user-level concept. And when we switch to Unicode,
-@c character sets in the current sense may not even exist.
-
-@findex list-charset-chars
-@cindex characters in a certain charset
- The command @kbd{M-x list-charset-chars} prompts for a name of a
-character set, and displays all the characters in that character set.
-
-@findex describe-character-set
-@cindex character set, description
- The command @kbd{M-x describe-character-set} prompts for a character
-set name and displays information about that character set, including
-its internal representation within Emacs.
-@end ignore
-
@node Enabling Multibyte
@section Enabling Multibyte Characters
-@cindex turn multibyte support on or off
- You can enable or disable multibyte character support, either for
-Emacs as a whole, or for a single buffer. When multibyte characters are
-disabled in a buffer, then each byte in that buffer represents a
-character, even codes 0200 through 0377. The old features for
-supporting the European character sets, ISO Latin-1 and ISO Latin-2,
-work as they did in Emacs 19 and also work for the other ISO 8859
-character sets.
-
- However, there is no need to turn off multibyte character support to
-use ISO Latin; the Emacs multibyte character set includes all the
-characters in these character sets, and Emacs can translate
-automatically to and from the ISO codes.
-
By default, Emacs starts in multibyte mode, because that allows you to
use all the supported languages and scripts without limitations.
+@cindex turn multibyte support on or off
+ You can enable or disable multibyte character support, either for
+Emacs as a whole, or for a single buffer. When multibyte characters
+are disabled in a buffer, we call that @dfn{unibyte mode}. Then each
+byte in that buffer represents a character, even codes 0200 through
+0377.
+
+ The old features for supporting the European character sets, ISO
+Latin-1 and ISO Latin-2, work in unibyte mode as they did in Emacs 19
+and also work for the other ISO 8859 character sets. However, there
+is no need to turn off multibyte character support to use ISO Latin;
+the Emacs multibyte character set includes all the characters in these
+character sets, and Emacs can translate automatically to and from the
+ISO codes.
+
To edit a particular file in unibyte representation, visit it using
@code{find-file-literally}. @xref{Visiting}. To convert a buffer in
multibyte representation into a single-byte representation of the same
buffer, and find the file again with @code{find-file-literally}. You
can also use @kbd{C-x @key{RET} c}
(@code{universal-coding-system-argument}) and specify @samp{raw-text} as
-the coding system with which to find or save a file. @xref{Specify
+the coding system with which to find or save a file. @xref{Text
Coding}. Finding a file as @samp{raw-text} doesn't disable format
conversion, uncompression and auto mode selection as
@code{find-file-literally} does.
@cindex Lisp files, and multibyte operation
@cindex multibyte operation, and Lisp files
@cindex unibyte operation, and Lisp files
-@cindex init file, and non-ASCII characters
-@cindex environment variables, and non-ASCII characters
+@cindex init file, and non-@acronym{ASCII} characters
+@cindex environment variables, and non-@acronym{ASCII} characters
With @samp{--unibyte}, multibyte strings are not created during
initialization from the values of environment variables,
-@file{/etc/passwd} entries etc.@: that contain non-ASCII 8-bit
+@file{/etc/passwd} entries etc.@: that contain non-@acronym{ASCII} 8-bit
characters.
Emacs normally loads Lisp files as multibyte, regardless of whether
-you used @samp{--unibyte}. This includes the Emacs initialization
-file, @file{.emacs}, and the initialization files of Emacs packages
-such as Gnus. However, you can specify unibyte loading for a
-particular Lisp file, by putting @w{@samp{-*-unibyte: t;-*-}} in a
-comment on the first line. Then that file is always loaded as unibyte
-text, even if you did not start Emacs with @samp{--unibyte}. The
-motivation for these conventions is that it is more reliable to always
-load any particular Lisp file in the same way. However, you can load
-a Lisp file as unibyte, on any one occasion, by typing @kbd{C-x
+you used @samp{--unibyte}. This includes the Emacs initialization file,
+@file{.emacs}, and the initialization files of Emacs packages such as
+Gnus. However, you can specify unibyte loading for a particular Lisp
+file, by putting @w{@samp{-*-unibyte: t;-*-}} in a comment on the first
+line (@pxref{File Variables}). Then that file is always loaded as
+unibyte text, even if you did not start Emacs with @samp{--unibyte}.
+The motivation for these conventions is that it is more reliable to
+always load any particular Lisp file in the same way. However, you can
+load a Lisp file as unibyte, on any one occasion, by typing @kbd{C-x
@key{RET} c raw-text @key{RET}} immediately before loading it.
- The mode line indicates whether multibyte character support is enabled
-in the current buffer. If it is, there are two or more characters (most
-often two dashes) before the colon near the beginning of the mode line.
-When multibyte characters are not enabled, just one dash precedes the
-colon.
+ The mode line indicates whether multibyte character support is
+enabled in the current buffer. If it is, there are two or more
+characters (most often two dashes) near the beginning of the mode
+line, before the indication of the visited file's end-of-line
+convention (colon, backslash, etc.). When multibyte characters
+are not enabled, nothing precedes the colon except a single dash.
+@xref{Mode Line}, for more details about this.
@node Language Environments
@section Language Environments
@findex set-language-environment
@vindex current-language-environment
- To select a language environment, customize the option
+ To select a language environment, you can customize the variable
@code{current-language-environment} or use the command @kbd{M-x
set-language-environment}. It makes no difference which buffer is
current when you use this command, because the effects apply globally to
the Emacs session. The supported language environments include:
@cindex Euro sign
+@cindex UTF-8
@quotation
-Chinese-BIG5, Chinese-CNS, Chinese-GB, Cyrillic-ALT, Cyrillic-ISO,
-Cyrillic-KOI8, Czech, Devanagari, Dutch, English, Ethiopic, German,
-Greek, Hebrew, IPA, Japanese, Korean, Lao, Latin-1, Latin-2, Latin-3,
-Latin-4, Latin-5, Latin-8 (Celtic), Latin-9 (updated Latin-1, with the
-Euro sign), Polish, Romanian, Slovak, Slovenian, Spanish, Thai,
-Tibetan, Turkish, and Vietnamese.
+ASCII, Belarusian, Brazilian Portuguese, Bulgarian, Chinese-BIG5,
+Chinese-CNS, Chinese-EUC-TW, Chinese-GB, Croatian, Cyrillic-ALT,
+Cyrillic-ISO, Cyrillic-KOI8, Czech, Devanagari, Dutch, English,
+Esperanto, Ethiopic, French, Georgian, German, Greek, Hebrew, IPA,
+Italian, Japanese, Kannada, Korean, Lao, Latin-1, Latin-2, Latin-3,
+Latin-4, Latin-5, Latin-6, Latin-7, Latin-8 (Celtic), Latin-9 (updated
+Latin-1 with the Euro sign), Latvian, Lithuanian, Malayalam, Polish,
+Romanian, Russian, Slovak, Slovenian, Spanish, Swedish, Tajik, Tamil,
+Thai, Tibetan, Turkish, UTF-8 (for a setup which prefers Unicode
+characters and files encoded in UTF-8), Ukrainian, Vietnamese, Welsh,
+and Windows-1255 (for a setup which prefers Cyrillic characters and
+files encoded in Windows-1255).
+@tex
+\hbadness=10000\par % just avoid underfull hbox warning
+@end tex
@end quotation
@cindex fonts for various scripts
To display the script(s) used by your language environment on a
graphical display, you need to have a suitable font. If some of the
characters appear as empty boxes, you should install the GNU Intlfonts
-package, which includes fonts for all supported scripts.@footnote{If
+package, which includes fonts for most supported scripts.@footnote{If
you run Emacs on X, you need to inform the X server about the location
of the newly installed fonts with the following commands:
@code{locale-charset-language-names} and @code{locale-language-names},
and selects the corresponding language environment if a match is found.
(The former variable overrides the latter.) It also adjusts the display
-table and terminal coding system, the locale coding system, and the
-preferred coding system as needed for the locale.
+table and terminal coding system, the locale coding system, the
+preferred coding system as needed for the locale, and---last but not
+least---the way Emacs decodes non-@acronym{ASCII} characters sent by your keyboard.
If you modify the @env{LC_ALL}, @env{LC_CTYPE}, or @env{LANG}
environment variables while running Emacs, you may want to invoke the
@findex describe-language-environment
To display information about the effects of a certain language
environment @var{lang-env}, use the command @kbd{C-h L @var{lang-env}
-@key{RET}} (@code{describe-language-environment}). This tells you which
-languages this language environment is useful for, and lists the
+@key{RET}} (@code{describe-language-environment}). This tells you
+which languages this language environment is useful for, and lists the
character sets, coding systems, and input methods that go with it. It
-also shows some sample text to illustrate scripts used in this language
-environment. By default, this command describes the chosen language
-environment.
+also shows some sample text to illustrate scripts used in this
+language environment. If you give an empty input for @var{lang-env},
+this command describes the chosen language environment.
@vindex set-language-environment-hook
You can customize any language environment with the normal hook
characters can share one input method. A few languages support several
input methods.
- The simplest kind of input method works by mapping ASCII letters
+ The simplest kind of input method works by mapping @acronym{ASCII} letters
into another alphabet; this allows you to use one other alphabet
-instead of ASCII. The Greek and Russian input methods
+instead of @acronym{ASCII}. The Greek and Russian input methods
work this way.
A more powerful technique is composition: converting sequences of
characters into one letter. Many European input methods use composition
-to produce a single non-ASCII letter from a sequence that consists of a
+to produce a single non-@acronym{ASCII} letter from a sequence that consists of a
letter followed by accent characters (or vice versa). For example, some
methods convert the sequence @kbd{a'} into a single accented letter.
These input methods have no special commands of their own; all they do
Another method, more general but not quite as easy to type, is to use
@kbd{C-\ C-\} between two characters to stop them from combining. This
is the command @kbd{C-\} (@code{toggle-input-method}) used twice.
-@ifinfo
+@ifnottex
@xref{Select Input Method}.
-@end ifinfo
+@end ifnottex
@cindex incremental search, input method interference
@kbd{C-\ C-\} is especially useful inside an incremental search,
because it stops waiting for more characters to combine, and starts
searching for what you have already entered.
+ To find out how to input the character after point using the current
+input method, type @kbd{C-u C-x =}. @xref{Position Info}.
+
@vindex input-method-verbose-flag
@vindex input-method-highlight-flag
The variables @code{input-method-highlight-flag} and
possible characters to type next is displayed in the echo area (but
not when you are in the minibuffer).
-@cindex Leim package
- Input methods are implemented in the separate Leim package: they are
-available only if the system administrator used Leim when building
-Emacs. If Emacs was built without Leim, you will find that no input
-methods are defined.
-
@node Select Input Method
@section Selecting an Input Method
input method name from the minibuffer; the name normally starts with the
language environment that it is meant to be used with. The variable
@code{current-input-method} records which input method is selected.
-
+
@findex toggle-input-method
@kindex C-\
- Input methods use various sequences of ASCII characters to stand for
-non-ASCII characters. Sometimes it is useful to turn off the input
-method temporarily. To do this, type @kbd{C-\}
+ Input methods use various sequences of @acronym{ASCII} characters to
+stand for non-@acronym{ASCII} characters. Sometimes it is useful to
+turn off the input method temporarily. To do this, type @kbd{C-\}
(@code{toggle-input-method}). To reenable the input method, type
@kbd{C-\} again.
actual keyboard layout. To specify which layout your keyboard has, use
the command @kbd{M-x quail-set-keyboard-layout}.
+@findex quail-show-key
+ You can use the command @kbd{M-x quail-show-key} to show what key (or
+key sequence) to type in order to input the character following point,
+using the selected keyboard layout. The command @kbd{C-u C-x =} also
+shows that information in addition to the other information about the
+character.
+
@findex list-input-methods
- To display a list of all the supported input methods, type @kbd{M-x
+ To see a list of all the supported input methods, type @kbd{M-x
list-input-methods}. The list gives information about each input
method, including the string that stands for it in the mode line.
@node Multibyte Conversion
-@section Unibyte and Multibyte Non-ASCII characters
+@section Unibyte and Multibyte Non-@acronym{ASCII} characters
When multibyte characters are enabled, character codes 0240 (octal)
through 0377 (octal) are not really legitimate in the buffer. The valid
-non-ASCII printing characters have codes that start from 0400.
+non-@acronym{ASCII} printing characters have codes that start from 0400.
If you type a self-inserting character in the range 0240 through
0377, or if you use @kbd{C-q} to insert one, Emacs assumes you
@iftex
(see above).
@end iftex
-@ifinfo
+@ifnottex
(@pxref{Language Environments}).
-@end ifinfo
+@end ifnottex
If you do not specify a choice, the default is Latin-1.
If you insert a character in the range 0200 through 0237, which
@cindex international files from DOS/Windows systems
A special class of coding systems, collectively known as
@dfn{codepages}, is designed to support text encoded by MS-Windows and
-MS-DOS software. To use any of these systems, you need to create it
-with @kbd{M-x codepage-setup}. @xref{MS-DOS and MULE}. After
-creating the coding system for the codepage, you can use it as any
-other coding system. For example, to visit a file encoded in codepage
-850, type @kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename}
-@key{RET}}.
-
- In addition to converting various representations of non-ASCII
+MS-DOS software. The names of these coding systems are
+@code{cp@var{nnnn}}, where @var{nnnn} is a 3- or 4-digit number of the
+codepage. You can use these encodings just like any other coding
+system; for example, to visit a file encoded in codepage 850, type
+@kbd{C-x @key{RET} c cp850 @key{RET} C-x C-f @var{filename}
+@key{RET}}@footnote{
+In the MS-DOS port of Emacs, you need to create a @code{cp@var{nnn}}
+coding system with @kbd{M-x codepage-setup}, before you can use it.
+@iftex
+@xref{MS-DOS and MULE,,,emacs-extra,Specialized Emacs Features}.
+@end iftex
+@ifnottex
+@xref{MS-DOS and MULE}.
+@end ifnottex
+}.
+
+ In addition to converting various representations of non-@acronym{ASCII}
characters, a coding system can perform end-of-line conversion. Emacs
handles three different conventions for how to separate lines in a file:
newline, carriage-return linefeed, and just carriage-return.
@kindex C-h C
@findex describe-coding-system
The command @kbd{C-h C} (@code{describe-coding-system}) displays
-information about particular coding systems. You can specify a coding
+information about particular coding systems, including the end-of-line
+conversion specified by those coding systems. You can specify a coding
system name as the argument; alternatively, with an empty argument, it
describes the coding systems currently selected for various purposes,
both in the current buffer and as the defaults, and the priority list
(@pxref{Mode Line}).
@cindex end-of-line conversion
+@cindex line endings
@cindex MS-DOS end-of-line conversion
@cindex Macintosh end-of-line conversion
Each of the coding systems that appear in this list---except for
variants @code{iso-latin-1-unix}, @code{iso-latin-1-dos} and
@code{iso-latin-1-mac}.
+@cindex @code{undecided}, coding system
+ The coding systems @code{unix}, @code{dos}, and @code{mac} are
+aliases for @code{undecided-unix}, @code{undecided-dos}, and
+@code{undecided-mac}, respectively. These coding systems specify only
+the end-of-line conversion, and leave the character code conversion to
+be deduced from the text itself.
+
The coding system @code{raw-text} is good for a file which is mainly
-ASCII text, but may contain byte values above 127 which are not meant to
-encode non-ASCII characters. With @code{raw-text}, Emacs copies those
-byte values unchanged, and sets @code{enable-multibyte-characters} to
-@code{nil} in the current buffer so that they will be interpreted
-properly. @code{raw-text} handles end-of-line conversion in the usual
-way, based on the data encountered, and has the usual three variants to
-specify the kind of end-of-line conversion to use.
+@acronym{ASCII} text, but may contain byte values above 127 which are
+not meant to encode non-@acronym{ASCII} characters. With
+@code{raw-text}, Emacs copies those byte values unchanged, and sets
+@code{enable-multibyte-characters} to @code{nil} in the current buffer
+so that they will be interpreted properly. @code{raw-text} handles
+end-of-line conversion in the usual way, based on the data
+encountered, and has the usual three variants to specify the kind of
+end-of-line conversion to use.
In contrast, the coding system @code{no-conversion} specifies no
-character code conversion at all---none for non-ASCII byte values and
+character code conversion at all---none for non-@acronym{ASCII} byte values and
none for end of line. This is useful for reading or writing binary
files, tar files, and other files that must be examined verbatim. It,
too, sets @code{enable-multibyte-characters} to @code{nil}.
might convert the file contents before you see them. @xref{Visiting}.
The coding system @code{emacs-mule} means that the file contains
-non-ASCII characters stored with the internal Emacs encoding. It
+non-@acronym{ASCII} characters stored with the internal Emacs encoding. It
handles end-of-line conversion based on the data encountered, and has
the usual three variants to specify the kind of end-of-line conversion.
+@findex unify-8859-on-decoding-mode
+@anchor{Character Translation}
+ The @dfn{character translation} feature can modify the effect of
+various coding systems, by changing the internal Emacs codes that
+decoding produces. For instance, the command
+@code{unify-8859-on-decoding-mode} enables a mode that ``unifies'' the
+Latin alphabets when decoding text. This works by converting all
+non-@acronym{ASCII} Latin-@var{n} characters to either Latin-1 or
+Unicode characters. This way it is easier to use various
+Latin-@var{n} alphabets together. (In a future Emacs version we hope
+to move towards full Unicode support and complete unification of
+character sets.)
+
+@vindex enable-character-translation
+ If you set the variable @code{enable-character-translation} to
+@code{nil}, that disables all character translation (including
+@code{unify-8859-on-decoding-mode}).
+
@node Recognize Coding
@section Recognizing Coding Systems
reasons to specify a language environment.
@findex prefer-coding-system
- However, you can alter the priority list in detail with the command
-@kbd{M-x prefer-coding-system}. This command reads the name of a coding
-system from the minibuffer, and adds it to the front of the priority
-list, so that it is preferred to all others. If you use this command
-several times, each use adds one element to the front of the priority
-list.
+ However, you can alter the coding system priority list in detail
+with the command @kbd{M-x prefer-coding-system}. This command reads
+the name of a coding system from the minibuffer, and adds it to the
+front of the priority list, so that it is preferred to all others. If
+you use this command several times, each use adds one element to the
+front of the priority list.
If you use a coding system that specifies the end-of-line conversion
type, such as @code{iso-8859-1-dos}, what this means is that Emacs
correspondence. There is a special function
@code{modify-coding-system-alist} for adding elements to this list. For
example, to read and write all @samp{.txt} files using the coding system
-@code{china-iso-8bit}, you can execute this Lisp expression:
+@code{chinese-iso-8bit}, you can execute this Lisp expression:
@smallexample
-(modify-coding-system-alist 'file "\\.txt\\'" 'china-iso-8bit)
+(modify-coding-system-alist 'file "\\.txt\\'" 'chinese-iso-8bit)
@end smallexample
@noindent
The default value of @code{inhibit-iso-escape-detection} is
@code{nil}. We recommend that you not change it permanently, only for
one specific operation. That's because many Emacs Lisp source files
-in the Emacs distribution contain non-ASCII characters encoded in the
+in the Emacs distribution contain non-@acronym{ASCII} characters encoded in the
coding system @code{iso-2022-7bit}, and they won't be
decoded correctly when you visit those files if you suppress the
escape sequence detection.
-@vindex coding
- You can specify the coding system for a particular file using the
-@w{@samp{-*-@dots{}-*-}} construct at the beginning of a file, or a
-local variables list at the end (@pxref{File Variables}). You do this
-by defining a value for the ``variable'' named @code{coding}. Emacs
-does not really have a variable @code{coding}; instead of setting a
-variable, this uses the specified coding system for the file. For
-example, @samp{-*-mode: C; coding: latin-1;-*-} specifies use of the
-Latin-1 coding system, as well as C mode. When you specify the coding
-explicitly in the file, that overrides
-@code{file-coding-system-alist}.
-
@vindex auto-coding-alist
@vindex auto-coding-regexp-alist
- The variables @code{auto-coding-alist} and
-@code{auto-coding-regexp-alist} are the strongest way to specify the
-coding system for certain patterns of file names, or for files
-containing certain patterns; these variables even override
-@samp{-*-coding:-*-} tags in the file itself. Emacs uses
-@code{auto-coding-alist} for tar and archive files, to prevent it
+@vindex auto-coding-functions
+ The variables @code{auto-coding-alist},
+@code{auto-coding-regexp-alist} and @code{auto-coding-functions} are
+the strongest way to specify the coding system for certain patterns of
+file names, or for files containing certain patterns; these variables
+even override @samp{-*-coding:-*-} tags in the file itself. Emacs
+uses @code{auto-coding-alist} for tar and archive files, to prevent it
from being confused by a @samp{-*-coding:-*-} tag in a member of the
archive and thinking it applies to the archive file as a whole.
Likewise, Emacs uses @code{auto-coding-regexp-alist} to ensure that
-RMAIL files, whose names in general don't match any particular pattern,
-are decoded correctly.
+RMAIL files, whose names in general don't match any particular
+pattern, are decoded correctly. One of the builtin
+@code{auto-coding-functions} detects the encoding for XML files.
+
+@vindex rmail-decode-mime-charset
+ When you get new mail in Rmail, each message is translated
+automatically from the coding system it is written in, as if it were a
+separate file. This uses the priority list of coding systems that you
+have specified. If a MIME message specifies a character set, Rmail
+obeys that specification, unless @code{rmail-decode-mime-charset} is
+@code{nil}.
+
+@vindex rmail-file-coding-system
+ For reading and saving Rmail files themselves, Emacs uses the coding
+system specified by the variable @code{rmail-file-coding-system}. The
+default value is @code{nil}, which means that Rmail files are not
+translated (they are read and written in the Emacs internal character
+code).
+
+@node Specify Coding
+@section Specifying a File's Coding System
If Emacs recognizes the encoding of a file incorrectly, you can
reread the file using the correct coding system by typing @kbd{C-x
-@key{RET} c @var{coding-system} @key{RET} M-x revert-buffer
-@key{RET}}. To see what coding system Emacs actually used to decode
-the file, look at the coding system mnemonic letter near the left edge
-of the mode line (@pxref{Mode Line}), or type @kbd{C-h C @key{RET}}.
+@key{RET} r @var{coding-system} @key{RET}}. To see what coding system
+Emacs actually used to decode the file, look at the coding system
+mnemonic letter near the left edge of the mode line (@pxref{Mode
+Line}), or type @kbd{C-h C @key{RET}}.
+
+@vindex coding
+ You can specify the coding system for a particular file in the file
+itself, using the @w{@samp{-*-@dots{}-*-}} construct at the beginning,
+or a local variables list at the end (@pxref{File Variables}). You do
+this by defining a value for the ``variable'' named @code{coding}.
+Emacs does not really have a variable @code{coding}; instead of
+setting a variable, this uses the specified coding system for the
+file. For example, @samp{-*-mode: C; coding: latin-1;-*-} specifies
+use of the Latin-1 coding system, as well as C mode. When you specify
+the coding explicitly in the file, that overrides
+@code{file-coding-system-alist}.
+
+ If you add the character @samp{!} at the end of the coding system
+name in @code{coding}, it disables any character translation
+(@pxref{Character Translation}) while decoding the file. This is
+useful when you need to make sure that the character codes in the
+Emacs buffer will not vary due to changes in user settings; for
+instance, for the sake of strings in Emacs Lisp source files.
+
+@node Output Coding
+@section Choosing Coding Systems for Output
@vindex buffer-file-coding-system
Once Emacs has chosen a coding system for a buffer, it stores that
-coding system in @code{buffer-file-coding-system} and uses that coding
-system, by default, for operations that write from this buffer into a
-file. This includes the commands @code{save-buffer} and
-@code{write-region}. If you want to write files from this buffer using
-a different coding system, you can specify a different coding system for
-the buffer using @code{set-buffer-file-coding-system} (@pxref{Specify
-Coding}).
-
- You can insert any possible character into any Emacs buffer, but
-most coding systems can only handle some of the possible characters.
-This means that it is possible for you to insert characters that
-cannot be encoded with the coding system that will be used to save the
-buffer. For example, you could start with an ASCII file and insert a
-few Latin-1 characters into it, or you could edit a text file in
-Polish encoded in @code{iso-8859-2} and add some Russian words to it.
-When you save the buffer, Emacs cannot use the current value of
+coding system in @code{buffer-file-coding-system}. That makes it the
+default for operations that write from this buffer into a file, such
+as @code{save-buffer} and @code{write-region}. You can specify a
+different coding system for further file output from the buffer using
+@code{set-buffer-file-coding-system} (@pxref{Text Coding}).
+
+ You can insert any character Emacs supports into any Emacs buffer,
+but most coding systems can only handle a subset of these characters.
+Therefore, you can insert characters that cannot be encoded with the
+coding system that will be used to save the buffer. For example, you
+could start with an @acronym{ASCII} file and insert a few Latin-1
+characters into it, or you could edit a text file in Polish encoded in
+@code{iso-8859-2} and add some Russian words to it. When you save
+that buffer, Emacs cannot use the current value of
@code{buffer-file-coding-system}, because the characters you added
cannot be encoded by that coding system.
If you insert the unsuitable characters in a mail message, Emacs
behaves a bit differently. It additionally checks whether the
most-preferred coding system is recommended for use in MIME messages;
-if not, Emacs tells you that the most-preferred coding system is
-not recommended and prompts you for another coding system. This is so
-you won't inadvertently send a message encoded in a way that your
-recipient's mail software will have difficulty decoding. (If you do
-want to use the most-preferred coding system, you can still type its
-name in response to the question.)
+if not, Emacs tells you that the most-preferred coding system is not
+recommended and prompts you for another coding system. This is so you
+won't inadvertently send a message encoded in a way that your
+recipient's mail software will have difficulty decoding. (You can
+still use an unsuitable coding system if you type its name in response
+to the question.)
@vindex sendmail-coding-system
When you send a message with Mail mode (@pxref{Sending Mail}), Emacs has
if that is non-@code{nil}. If all of these three values are @code{nil},
Emacs encodes outgoing mail using the Latin-1 coding system.
-@vindex rmail-decode-mime-charset
- When you get new mail in Rmail, each message is translated
-automatically from the coding system it is written in, as if it were a
-separate file. This uses the priority list of coding systems that you
-have specified. If a MIME message specifies a character set, Rmail
-obeys that specification, unless @code{rmail-decode-mime-charset} is
-@code{nil}.
-
-@vindex rmail-file-coding-system
- For reading and saving Rmail files themselves, Emacs uses the coding
-system specified by the variable @code{rmail-file-coding-system}. The
-default value is @code{nil}, which means that Rmail files are not
-translated (they are read and written in the Emacs internal character
-code).
-
-@node Specify Coding
-@section Specifying a Coding System
+@node Text Coding
+@section Specifying a Coding System for File Text
In cases where Emacs does not automatically choose the right coding
-system, you can use these commands to specify one:
+system for a file's contents, you can use these commands to specify
+one:
@table @kbd
@item C-x @key{RET} f @var{coding} @key{RET}
-Use coding system @var{coding} for the visited file
-in the current buffer.
+Use coding system @var{coding} for saving or revisiting the visited
+file in the current buffer.
@item C-x @key{RET} c @var{coding} @key{RET}
Specify coding system @var{coding} for the immediately following
command.
-@item C-x @key{RET} k @var{coding} @key{RET}
-Use coding system @var{coding} for keyboard input.
-
-@item C-x @key{RET} t @var{coding} @key{RET}
-Use coding system @var{coding} for terminal output.
-
-@item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET}
-Use coding systems @var{input-coding} and @var{output-coding} for
-subprocess input and output in the current buffer.
-
-@item C-x @key{RET} x @var{coding} @key{RET}
-Use coding system @var{coding} for transferring selections to and from
-other programs through the window system.
+@item C-x @key{RET} r @var{coding} @key{RET}
+Revisit the current file using the coding system @var{coding}.
-@item C-x @key{RET} X @var{coding} @key{RET}
-Use coding system @var{coding} for transferring @emph{one}
-selection---the next one---to or from the window system.
+@item M-x recode-region @key{RET} @var{right} @key{RET} @var{wrong} @key{RET}
+Convert a region that was decoded using coding system @var{wrong},
+decoding it using coding system @var{right} instead.
@end table
@kindex C-x RET f
@findex set-buffer-file-coding-system
- The command @kbd{C-x @key{RET} f} (@code{set-buffer-file-coding-system})
-specifies the file coding system for the current buffer---in other
-words, which coding system to use when saving or rereading the visited
-file. You specify which coding system using the minibuffer. Since this
-command applies to a file you have already visited, it affects only the
-way the file is saved.
+ The command @kbd{C-x @key{RET} f}
+(@code{set-buffer-file-coding-system}) sets the file coding system for
+the current buffer---in other words, it says which coding system to
+use when saving or reverting the visited file. You specify which
+coding system using the minibuffer. If you specify a coding system
+that cannot handle all of the characters in the buffer, Emacs warns
+you about the troublesome characters when you actually save the
+buffer.
+
+@cindex specify end-of-line conversion
+ You can also use this command to specify the end-of-line conversion
+(@pxref{Coding Systems, end-of-line conversion}) for encoding the
+current buffer. For example, @kbd{C-x @key{RET} f dos @key{RET}} will
+cause Emacs to save the current buffer's text with DOS-style CRLF line
+endings.
@kindex C-x RET c
@findex universal-coding-system-argument
So if the immediately following command is @kbd{C-x C-f}, for example,
it reads the file using that coding system (and records the coding
-system for when the file is saved). Or if the immediately following
+system for when you later save the file). Or if the immediately following
command is @kbd{C-x C-w}, it writes the file using that coding system.
-Other file commands affected by a specified coding system include
-@kbd{C-x C-i} and @kbd{C-x C-v}, as well as the other-window variants of
-@kbd{C-x C-f}.
+When you specify the coding system for saving in this way, instead
+of with @kbd{C-x @key{RET} f}, there is no warning if the buffer
+contains characters that the coding system cannot handle.
- @kbd{C-x @key{RET} c} also affects commands that start subprocesses,
-including @kbd{M-x shell} (@pxref{Shell}).
-
- However, if the immediately following command does not use the coding
-system, then @kbd{C-x @key{RET} c} ultimately has no effect.
+ Other file commands affected by a specified coding system include
+@kbd{C-x i} and @kbd{C-x C-v}, as well as the other-window variants
+of @kbd{C-x C-f}. @kbd{C-x @key{RET} c} also affects commands that
+start subprocesses, including @kbd{M-x shell} (@pxref{Shell}). If the
+immediately following command does not use the coding system, then
+@kbd{C-x @key{RET} c} ultimately has no effect.
An easy way to visit a file with no conversion is with the @kbd{M-x
find-file-literally} command. @xref{Visiting}.
variable to a good choice of default coding system for that language
environment.
-@kindex C-x RET t
-@findex set-terminal-coding-system
- The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system})
-specifies the coding system for terminal output. If you specify a
-character code for terminal output, all characters output to the
-terminal are translated into that coding system.
+@kindex C-x RET r
+@findex revert-buffer-with-coding-system
+ If you visit a file with a wrong coding system, you can correct this
+with @kbd{C-x @key{RET} r} (@code{revert-buffer-with-coding-system}).
+This visits the current file again, using a coding system you specify.
- This feature is useful for certain character-only terminals built to
-support specific languages or character sets---for example, European
-terminals that support one of the ISO Latin character sets. You need to
-specify the terminal coding system when using multibyte text, so that
-Emacs knows which characters the terminal can actually handle.
+@findex recode-region
+ If a piece of text has already been inserted into a buffer using the
+wrong coding system, you can redo the decoding of it using @kbd{M-x
+recode-region}. This prompts you for the proper coding system, then
+for the wrong coding system that was actually used, and does the
+conversion. It first encodes the region using the wrong coding system,
+then decodes it again using the proper coding system.
- By default, output to the terminal is not translated at all, unless
-Emacs can deduce the proper coding system from your terminal type or
-your locale specification (@pxref{Language Environments}).
+@node Communication Coding
+@section Coding Systems for Interprocess Communication
-@kindex C-x RET k
-@findex set-keyboard-coding-system
-@vindex keyboard-coding-system
- The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system})
-or the Custom option @code{keyboard-coding-system}
-specifies the coding system for keyboard input. Character-code
-translation of keyboard input is useful for terminals with keys that
-send non-ASCII graphic characters---for example, some terminals designed
-for ISO Latin-1 or subsets of it.
+ This section explains how to specify coding systems for use
+in communication with other processes.
- By default, keyboard input is not translated at all.
+@table @kbd
+@item C-x @key{RET} x @var{coding} @key{RET}
+Use coding system @var{coding} for transferring selections to and from
+other window-based applications.
- There is a similarity between using a coding system translation for
-keyboard input, and using an input method: both define sequences of
-keyboard input that translate into single characters. However, input
-methods are designed to be convenient for interactive use by humans, and
-the sequences that are translated are typically sequences of ASCII
-printing characters. Coding systems typically translate sequences of
-non-graphic characters.
+@item C-x @key{RET} X @var{coding} @key{RET}
+Use coding system @var{coding} for transferring @emph{one}
+selection---the next one---to or from another window-based application.
+
+@item C-x @key{RET} p @var{input-coding} @key{RET} @var{output-coding} @key{RET}
+Use coding systems @var{input-coding} and @var{output-coding} for
+subprocess input and output in the current buffer.
+
+@item C-x @key{RET} c @var{coding} @key{RET}
+Specify coding system @var{coding} for the immediately following
+command.
+@end table
@kindex C-x RET x
@kindex C-x RET X
@findex set-selection-coding-system
@findex set-next-selection-coding-system
The command @kbd{C-x @key{RET} x} (@code{set-selection-coding-system})
-specifies the coding system for sending selected text to the window
-system, and for receiving the text of selections made in other
+specifies the coding system for sending selected text to other windowing
+applications, and for receiving the text of selections made in other
applications. This command applies to all subsequent selections, until
you override it by using the command again. The command @kbd{C-x
@key{RET} X} (@code{set-next-selection-coding-system}) specifies the
and from a particular subprocess by giving the command in the
corresponding buffer.
+ You can also use @kbd{C-x @key{RET} c} just before the command that
+runs or starts a subprocess, to specify the coding system to use for
+communication with that subprocess.
+
The default for translation of process input and output depends on the
current language environment.
+@vindex locale-coding-system
+@cindex decoding non-@acronym{ASCII} keyboard input on X
+ The variable @code{locale-coding-system} specifies a coding system
+to use when encoding and decoding system strings such as system error
+messages and @code{format-time-string} formats and time stamps. That
+coding system is also used for decoding non-@acronym{ASCII} keyboard input on X
+Window systems. You should choose a coding system that is compatible
+with the underlying system's text representation, which is normally
+specified by one of the environment variables @env{LC_ALL},
+@env{LC_CTYPE}, and @env{LANG}. (The first one, in the order
+specified above, whose value is nonempty is the one that determines
+the text representation.)
+
+@node File Name Coding
+@section Coding Systems for File Names
+
+@table @kbd
+@item C-x @key{RET} F @var{coding} @key{RET}
+Use coding system @var{coding} for encoding and decoding file
+@emph{names}.
+@end table
+
@vindex file-name-coding-system
-@cindex file names with non-ASCII characters
- The variable @code{file-name-coding-system} specifies a coding system
-to use for encoding file names. If you set the variable to a coding
-system name (as a Lisp symbol or a string), Emacs encodes file names
-using that coding system for all file operations. This makes it
-possible to use non-ASCII characters in file names---or, at least, those
-non-ASCII characters which the specified coding system can encode.
-
- If @code{file-name-coding-system} is @code{nil}, Emacs uses a default
-coding system determined by the selected language environment. In the
-default language environment, any non-ASCII characters in file names are
-not encoded specially; they appear in the file system using the internal
-Emacs representation.
+@cindex file names with non-@acronym{ASCII} characters
+ The variable @code{file-name-coding-system} specifies a coding
+system to use for encoding file names. It has no effect on reading
+and writing the @emph{contents} of files.
+
+@findex set-file-name-coding-system
+@kindex C-x @key{RET} F
+ If you set the variable to a coding system name (as a Lisp symbol or
+a string), Emacs encodes file names using that coding system for all
+file operations. This makes it possible to use non-@acronym{ASCII}
+characters in file names---or, at least, those non-@acronym{ASCII}
+characters which the specified coding system can encode. Use @kbd{C-x
+@key{RET} F} (@code{set-file-name-coding-system}) to specify this
+interactively.
+
+ If @code{file-name-coding-system} is @code{nil}, Emacs uses a
+default coding system determined by the selected language environment.
+In the default language environment, any non-@acronym{ASCII}
+characters in file names are not encoded specially; they appear in the
+file system using the internal Emacs representation.
@strong{Warning:} if you change @code{file-name-coding-system} (or the
language environment) in the middle of an Emacs session, problems can
name, or it may get an error. If such a problem happens, use @kbd{C-x
C-w} to specify a new file name for that buffer.
-@vindex locale-coding-system
- The variable @code{locale-coding-system} specifies a coding system
-to use when encoding and decoding system strings such as system error
-messages and @code{format-time-string} formats and time stamps. You
-should choose a coding system that is compatible with the underlying
-system's text representation, which is normally specified by one of
-the environment variables @env{LC_ALL}, @env{LC_CTYPE}, and
-@env{LANG}. (The first one, in the order specified above, whose value
-is nonempty is the one that determines the text representation.)
+@findex recode-file-name
+ If a mistake occurs when encoding a file name, use the command
+@kbd{M-x recode-file-name} to change the file name's coding
+system. This prompts for an existing file name, its old coding
+system, and the coding system to which you wish to convert.
+
+@node Terminal Coding
+@section Coding Systems for Terminal I/O
+
+@table @kbd
+@item C-x @key{RET} k @var{coding} @key{RET}
+Use coding system @var{coding} for keyboard input.
+
+@item C-x @key{RET} t @var{coding} @key{RET}
+Use coding system @var{coding} for terminal output.
+@end table
+
+@kindex C-x RET t
+@findex set-terminal-coding-system
+ The command @kbd{C-x @key{RET} t} (@code{set-terminal-coding-system})
+specifies the coding system for terminal output. If you specify a
+character code for terminal output, all characters output to the
+terminal are translated into that coding system.
+
+ This feature is useful for certain character-only terminals built to
+support specific languages or character sets---for example, European
+terminals that support one of the ISO Latin character sets. You need to
+specify the terminal coding system when using multibyte text, so that
+Emacs knows which characters the terminal can actually handle.
+
+ By default, output to the terminal is not translated at all, unless
+Emacs can deduce the proper coding system from your terminal type or
+your locale specification (@pxref{Language Environments}).
+
+@kindex C-x RET k
+@findex set-keyboard-coding-system
+@vindex keyboard-coding-system
+ The command @kbd{C-x @key{RET} k} (@code{set-keyboard-coding-system})
+or the variable @code{keyboard-coding-system} specifies the coding
+system for keyboard input. Character-code translation of keyboard
+input is useful for terminals with keys that send non-@acronym{ASCII}
+graphic characters---for example, some terminals designed for ISO
+Latin-1 or subsets of it.
+
+ By default, keyboard input is translated based on your system locale
+setting. If your terminal does not really support the encoding
+implied by your locale (for example, if you find it inserts a
+non-@acronym{ASCII} character if you type @kbd{M-i}), you will need to set
+@code{keyboard-coding-system} to @code{nil} to turn off encoding.
+You can do this by putting
+
+@lisp
+(set-keyboard-coding-system nil)
+@end lisp
+
+@noindent
+in your @file{~/.emacs} file.
+
+ There is a similarity between using a coding system translation for
+keyboard input, and using an input method: both define sequences of
+keyboard input that translate into single characters. However, input
+methods are designed to be convenient for interactive use by humans, and
+the sequences that are translated are typically sequences of @acronym{ASCII}
+printing characters. Coding systems typically translate sequences of
+non-graphic characters.
@node Fontsets
@section Fontsets
@cindex fontsets
- A font for X typically defines shapes for a single alphabet or script.
+ A font typically defines shapes for a single alphabet or script.
Therefore, displaying the entire range of scripts that Emacs supports
requires a collection of many fonts. In Emacs, such a collection is
called a @dfn{fontset}. A fontset is defined by a list of fonts, each
assigned to handle a range of character codes.
- Each fontset has a name, like a font. The available X fonts are
-defined by the X server; fontsets, however, are defined within Emacs
-itself. Once you have defined a fontset, you can use it within Emacs by
-specifying its name, anywhere that you could use a single font. Of
-course, Emacs fontsets can use only the fonts that the X server
-supports; if certain characters appear on the screen as hollow boxes,
-this means that the fontset in use for them has no font for those
-characters.@footnote{The Emacs installation instructions have information on
-additional font support.}
+ Each fontset has a name, like a font. However, while fonts are
+stored in the system and the available font names are defined by the
+system, fontsets are defined within Emacs itself. Once you have
+defined a fontset, you can use it within Emacs by specifying its name,
+anywhere that you could use a single font. Of course, Emacs fontsets
+can use only the fonts that the system supports; if certain characters
+appear on the screen as hollow boxes, this means that the fontset in
+use for them has no font for those characters.@footnote{The Emacs
+installation instructions have information on additional font
+support.}
Emacs creates two fontsets automatically: the @dfn{standard fontset}
and the @dfn{startup fontset}. The standard fontset is most likely to
-have fonts for a wide variety of non-ASCII characters; however, this is
-not the default for Emacs to use. (By default, Emacs tries to find a
-font that has bold and italic variants.) You can specify use of the
-standard fontset with the @samp{-fn} option, or with the @samp{Font} X
-resource (@pxref{Font X}). For example,
+have fonts for a wide variety of non-@acronym{ASCII} characters;
+however, this is not the default for Emacs to use. (By default, Emacs
+tries to find a font that has bold and italic variants.) You can
+specify use of the standard fontset with the @samp{-fn} option. For
+example,
@example
emacs -fn fontset-standard
@end example
+@noindent
+You can also specify a fontset with the @samp{Font} resource (@pxref{X
+Resources}).
+
A fontset does not necessarily specify a font for every character
code. If a fontset specifies no font for a certain character, or if it
specifies a font that does not exist on your system, then it cannot
display that character properly. It will display that character as an
empty box instead.
-@vindex highlight-wrong-size-font
- The fontset height and width are determined by the ASCII characters
-(that is, by the font used for ASCII characters in that fontset). If
-another font in the fontset has a different height, or a different
-width, then characters assigned to that font are clipped to the
-fontset's size. If @code{highlight-wrong-size-font} is non-@code{nil},
-a box is displayed around these wrong-size characters as well.
-
@node Defining Fontsets
@section Defining fontsets
@samp{medium}, or @samp{i} instead of @samp{r}, or both.
@cindex startup fontset
- If you specify a default ASCII font with the @samp{Font} resource or
+ If you specify a default @acronym{ASCII} font with the @samp{Font} resource or
the @samp{-fn} argument, Emacs generates a fontset from it
automatically. This is the @dfn{startup fontset} and its name is
@code{fontset-startup}. It does this by replacing the @var{foundry},
The resource value should have this form:
@smallexample
-@var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}}
+@var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}}
@end smallexample
@noindent
For the other character sets, Emacs chooses a font based on
@var{fontpattern}. It replaces @samp{fontset-@var{alias}} with values
-that describe the character set. For the ASCII character font,
+that describe the character set. For the @acronym{ASCII} character font,
@samp{fontset-@var{alias}} is replaced with @samp{ISO8859-1}.
In addition, when several consecutive fields are wildcards, Emacs
@end example
@noindent
-the font specification for ASCII characters would be this:
+the font specification for @acronym{ASCII} characters would be this:
@example
-*-fixed-medium-r-normal-*-24-*-ISO8859-1
@node Undisplayable Characters
@section Undisplayable Characters
- Your terminal may be unable to display some non-@sc{ascii}
-characters. Most non-windowing terminals can only use a single
-character set (use the variable @code{default-terminal-coding-system}
-(@pxref{Specify Coding}) to tell Emacs which one); characters which
+ There may be a some non-@acronym{ASCII} characters that your terminal cannot
+display. Most text-only terminals support just a single character
+set (use the variable @code{default-terminal-coding-system}
+(@pxref{Terminal Coding}) to tell Emacs which one); characters which
can't be encoded in that coding system are displayed as @samp{?} by
default.
- Windowing terminals can display a broader range of characters, but
+ Graphical displays can display a broader range of characters, but
you may not have fonts installed for all of them; characters that have
no font appear as a hollow box.
If you use Latin-1 characters but your terminal can't display
-Latin-1, you can arrange to display mnemonic @sc{ascii} sequences
+Latin-1, you can arrange to display mnemonic @acronym{ASCII} sequences
instead, e.g.@: @samp{"o} for o-umlaut. Load the library
@file{iso-ascii} to do this.
@vindex latin1-display
If your terminal can display Latin-1, you can display characters
from other European character sets using a mixture of equivalent
-Latin-1 characters and ASCII mnemonics. Use the Custom option
-@code{latin1-display} to enable this. The mnemonic ASCII
+Latin-1 characters and @acronym{ASCII} mnemonics. Customize the variable
+@code{latin1-display} to enable this. The mnemonic @acronym{ASCII}
sequences mostly correspond to those of the prefix input methods.
-@node Single-Byte Character Support
-@section Single-byte Character Set Support
+@node Unibyte Mode
+@section Unibyte Editing Mode
@cindex European character sets
@cindex accented characters
For more information about unibyte operation, see @ref{Enabling
Multibyte}. Note particularly that you probably want to ensure that
-your initialization files are read as unibyte if they contain non-ASCII
-characters.
+your initialization files are read as unibyte if they contain
+non-@acronym{ASCII} characters.
@vindex unibyte-display-via-language-environment
Emacs can also display those characters, provided the terminal or font
-in use supports them. This works automatically. Alternatively, if you
-are using a window system, Emacs can also display single-byte characters
+in use supports them. This works automatically. Alternatively, on a
+graphical display, Emacs can also display single-byte characters
through fontsets, in effect by displaying the equivalent multibyte
characters according to the current language environment. To request
this, set the variable @code{unibyte-display-via-language-environment}
@cindex @code{iso-ascii} library
If your terminal does not support display of the Latin-1 character
-set, Emacs can display these characters as ASCII sequences which at
+set, Emacs can display these characters as @acronym{ASCII} sequences which at
least give you a clear idea of what the characters are. To do this,
load the library @code{iso-ascii}. Similar libraries for other
Latin-@var{n} character sets could be implemented, but we don't have
non-standard ``extended'' versions of ISO-8859 character sets by using the
function @code{standard-display-8bit} in the @code{disp-table} library.
- There are several ways you can input single-byte non-ASCII
+ There are two ways to input single-byte non-@acronym{ASCII}
characters:
@itemize @bullet
@cindex 8-bit input
+@item
+You can use an input method for the selected language environment.
+@xref{Input Methods}. When you use an input method in a unibyte buffer,
+the non-@acronym{ASCII} character you specify with it is converted to unibyte.
+
@item
If your keyboard can generate character codes 128 (decimal) and up,
-representing non-ASCII characters, you can type those character codes
+representing non-@acronym{ASCII} characters, you can type those character codes
directly.
-On a windowing terminal, you should not need to do anything special to
-use these keys; they should simply work. On a text-only terminal, you
+On a graphical display, you should not need to do anything special to use
+these keys; they should simply work. On a text-only terminal, you
should use the command @code{M-x set-keyboard-coding-system} or the
-Custom option @code{keyboard-coding-system} to specify which coding
-system your keyboard uses (@pxref{Specify Coding}). Enabling this
-feature will probably require you to use @kbd{ESC} to type Meta
-characters; however, on a Linux console or in @code{xterm}, you can
-arrange for Meta to be converted to @kbd{ESC} and still be able type
-8-bit characters present directly on the keyboard or using
-@kbd{Compose} or @kbd{AltGr} keys. @xref{User Input}.
-
-@item
-You can use an input method for the selected language environment.
-@xref{Input Methods}. When you use an input method in a unibyte buffer,
-the non-ASCII character you specify with it is converted to unibyte.
+variable @code{keyboard-coding-system} to specify which coding system
+your keyboard uses (@pxref{Terminal Coding}). Enabling this feature
+will probably require you to use @kbd{ESC} to type Meta characters;
+however, on a console terminal or in @code{xterm}, you can arrange for
+Meta to be converted to @kbd{ESC} and still be able type 8-bit
+characters present directly on the keyboard or using @kbd{Compose} or
+@kbd{AltGr} keys. @xref{User Input}.
@kindex C-x 8
@cindex @code{iso-transl} library
@cindex compose character
@cindex dead character
@item
-For Latin-1 only, you can use the
-key @kbd{C-x 8} as a ``compose character'' prefix for entry of
-non-ASCII Latin-1 printing characters. @kbd{C-x 8} is good for
-insertion (in the minibuffer as well as other buffers), for searching,
-and in any other context where a key sequence is allowed.
+For Latin-1 only, you can use the key @kbd{C-x 8} as a ``compose
+character'' prefix for entry of non-@acronym{ASCII} Latin-1 printing
+characters. @kbd{C-x 8} is good for insertion (in the minibuffer as
+well as other buffers), for searching, and in any other context where
+a key sequence is allowed.
@kbd{C-x 8} works by loading the @code{iso-transl} library. Once that
-library is loaded, the @key{ALT} modifier key, if you have one, serves
-the same purpose as @kbd{C-x 8}; use @key{ALT} together with an accent
-character to modify the following letter. In addition, if you have keys
-for the Latin-1 ``dead accent characters,'' they too are defined to
-compose with the following character, once @code{iso-transl} is loaded.
-Use @kbd{C-x 8 C-h} to list the available translations as mnemonic
-command names.
-
-@item
-@cindex @code{iso-acc} library
-@cindex ISO Accents mode
-@findex iso-accents-mode
-@cindex Latin-1, Latin-2 and Latin-3 input mode
-For Latin-1, Latin-2 and Latin-3, @kbd{M-x iso-accents-mode} enables
-a minor mode that works much like the @code{latin-1-prefix} input
-method, but does not depend on having the input methods installed. This
-mode is buffer-local. It can be customized for various languages with
-@kbd{M-x iso-accents-customize}.
+library is loaded, the @key{ALT} modifier key, if the keyboard has
+one, serves the same purpose as @kbd{C-x 8}: use @key{ALT} together
+with an accent character to modify the following letter. In addition,
+if the keyboard has keys for the Latin-1 ``dead accent characters,''
+they too are defined to compose with the following character, once
+@code{iso-transl} is loaded.
+
+Use @kbd{C-x 8 C-h} to list all the available @kbd{C-x 8} translations.
@end itemize
+
+@node Charsets
+@section Charsets
+@cindex charsets
+
+ Emacs groups all supported characters into disjoint @dfn{charsets}.
+Each character code belongs to one and only one charset. For
+historical reasons, Emacs typically divides an 8-bit character code
+for an extended version of @acronym{ASCII} into two charsets:
+@acronym{ASCII}, which covers the codes 0 through 127, plus another
+charset which covers the ``right-hand part'' (the codes 128 and up).
+For instance, the characters of Latin-1 include the Emacs charset
+@code{ascii} plus the Emacs charset @code{latin-iso8859-1}.
+
+ Emacs characters belonging to different charsets may look the same,
+but they are still different characters. For example, the letter
+@samp{o} with acute accent in charset @code{latin-iso8859-1}, used for
+Latin-1, is different from the letter @samp{o} with acute accent in
+charset @code{latin-iso8859-2}, used for Latin-2.
+
+@findex list-charset-chars
+@cindex characters in a certain charset
+@findex describe-character-set
+ There are two commands for obtaining information about Emacs
+charsets. The command @kbd{M-x list-charset-chars} prompts for a name
+of a character set, and displays all the characters in that character
+set. The command @kbd{M-x describe-character-set} prompts for a
+charset name and displays information about that charset, including
+its internal representation within Emacs.
+
+ To find out which charset a character in the buffer belongs to,
+put point before it and type @kbd{C-u C-x =}.
+
+@ignore
+ arch-tag: 310ba60d-31ef-4ce7-91f1-f282dd57b6b3
+@end ignore
HCoop / bpt / emacs.git / blobdiff